Four patients with pathologically proven retroperitoneal liposarcomas were examined by CT. The variabledensities of liposarcomas were closely correlated with their tissue component. Well differentiated liposarcoma waspredominently composed of fat denstiy, where as plemorphic liposarcomas were of higher densities than fat. Liposarcomas often included more than one type of tumor tissue, resulting in masses of different densitiescoexisting within the same mass. CT scan can provide informations about the location, size, extent, component ofthe tumor, relationship with adjacent anatomic structure, the presence of metastasis, in diagnosing this tumor.